Malignant melanoma is the least frequent but the most aggressive and deadliest form of skin cancer. Early detection and accurate staging are therefore crucial to ensure timely intervention and a good prognosis. Our long-term goal is to develop a microRNA (miRNA) -based assay for the accurate staging of cutaneous malignant melanoma. To accomplish this goal, we will identify a panel of sensitive melanoma- or melanocyte-specific miRNA markers for the detection of melanoma metastases in lymph nodes. The presence of lymph node metastasis predicts clinical outcome and is therefore the most important prognostic factor in melanoma. Current methods of ultra-staging involving sentinel lymph node biopsy combined with histopathology and immunohistochemistry are being used to improve staging and more accurately predict outcome. Recent studies in melanoma have shown that molecular analysis of the SLN allows earlier detection of nodal micrometastasis and predicts clinical outcome. The clinical significance of micrometastases is now being supported by a growing number of reports, suggesting that molecular markers will become important staging tools. miRNAs are small (19-23 nt), genetically-encoded RNA molecules that act as key regulators of gene expression and have been shown to be involved in a wide variety of cancers. Due to their roles in cancer processes as well as the observed stability and ready isolation of miRNAs from fixed tissues, miRNA appear to be good markers for diagnostic assays. Our preliminary data show that miRNAs can distinguish positive from negative (normal) lymph nodes in cutaneous malignant melanoma patients. Using microarrays and qRT-PCR, we have identified several miRNAs that are over-expressed by 30-fold or more in melanoma-positive lymph nodes. In this proposal, we describe our plans to develop a miRNA-based assay for the detection of melanoma metastases in lymph nodes. We will accomplish this by performing comprehensive marker discovery efforts using a well-annotated set of melanoma lymph node samples using our DiscovArray miRNA profiling service. We will subsequently validate these markers using a large independent set of samples using qRT-PCR. Performance of the markers will be compared to existing diagnostic procedures. Successful completion will lead to a marker panel that is ready to be launched as a diagnostic assay through our CLIA laboratory. Phase II will permit additional diagnostic kit development and clinical validation supporting commercialization as an approved IVD test. PUBLIC HEALTH RELEVANCE: The goal of this proposal is to develop diagnostic markers to detect melanoma cells in lymph nodes from melanoma patients. Lymph node metastases are a primary factor in the prognosis of patients and the decision to perform complete lymph node removal as well as choosing appropriate therapy and monitoring. This work will result in a diagnostic assay that will aid physicians in choosing appropriate treatment and monitoring for melanoma patients.